Reversing mechanism for machine tools



Feb. 7, 1933. 'c. T. RAULE 1,896,752

REVERSING MECHANISM FOR MACHINE TOOLS Filed Oct. 7, 1926 5 Sheets-Sheetl Feb. 7, 1933. T, RA 1,896,752

REVERSING MECHANISM FOR MACHINE TOOLS Filed Oct. 7 1926 5 Sheets-Sheet 3Fgb. 7, 1933. c. T. RAULE 1,896,752

' REVERSING MECHANISM FOR MACHINE TOOLS Filed Oct. 7; 1926 5Sheets-Sheet 4 Feb. 7, 1933. c. T. RAULE 1,896,752

REVERSING MECHANISM FOR MACHINE TOOLS Filed Oct. 7, 1926 5 Sheets-Sheet5 Patented Feb. 7, 1933 PATENT OFFICE i CLIFFORD T. RAULE, F BROOKLINE,PENNSYLVANIA REVERSING MECHANISM FOR MACHINE TOOLS Application filedOctober 7, 1926. Serial No. 140,035.

My invention relates to the traverse reversing mechanisms such as areused to reverse the feed of a grinding machine, lathe, boring bar,planer, shaper or other tool having repeated strokes over the same work.

The purpose of my invention is to cause the reversal by the stoppage ofa carriage carrying the work, the tool or other traversely movable part.

A further purpose is to cause the feeding mechanism of a machine tothrow the reversing mechanism after the carriage has stopped, shiftingthe feeding mechanism bodily or not as preferred.

A further purpose is to utilize a quick throw or full-stroke mechanismor an outside force to cause the final engagement of the parts.

A further purpose is to adapt my revers- 20 ing mechanism to applicationby mechanical, electrical, hydraulic or pneumatic means.

A further purpose is to utilize reversely cut threads upon the same leadscrew to operate driving mechanisms with which the carriage is caused toengage alternately.

A further purpose is to move a lead screw bodily by its own operation tocause a re versa] in its rotation or a shift in the clutch mechanismengaging it.

A further purpose is to operate a carriage in reverse directions from alead screw reversing it in direction of rotation by clutch mechanismsoperated by the lead screw.

A further purpose is to provide a separate driving motor for a leadscrew to control the direction of rotation of the driving motor bystoppage of the carriage.

Further purposes will appear in the specification and in the claims. Y

Figure l is a side elevation, partly broken away, of an internalgrinding machine in which my invention is well suited to operate.

Figures 2 and 3 are top plan view and end 5 elevation respectively ofthe structure seen in Figure 1.

Figures 4, 10, 11, 12, 13 and 14 are fragmentary longitudinal sectionsshowing a variety of structures by which my invention can be carriedout.

Figure 5 is a section of Figure 4 upon line Figure 6 is a fragmentarysection showing a modification of the structure of Figure 4.

Figure 7 is a fragmentary section of a modified thread.

Figures 8 and 9 are sections corresponding to Figure 4 but with theparts in different positions. a

Figure 15 is a fragmentary side elevation of a portion of a lathe.

In the drawings similar numerals indicate like parts.

I have preferred to illustrate my inven-- tion by a few only of the manyforms in which it may be carried out, selecting forms with a view toshowing respectively mechanical, electrical, hydraulic and pneumaticmechanisms, not from the standpoint of attempt ing to show all thedifferent forms, but to illustrate merely the fact that the inventionmay appear "in a variety of quite diverse forms.

I have selected the forms with a view' to illustration of the principlesinvolved to the best advantage. I

The frame 15 of the grinding machine presents no novelty in itsapplication to the invention in hand.. It carries a work head 16carrying the guard 17 within which the work 'is mounted, also bed 18 andguides 19 upon which a carriage travels. The carriage 20 is shown asprovided with two transverse slides 21 and 22, upon the upper one ofwhich is mounted the wheel head 23. The wheel 24 is driven by a motornot shown. As this invention has to do with the reversing mechanism itis not concerned with the character of these devices.

Travel of the work head longitudinally on guides 25 is controlled by ahand wheel 26, rack 27 and gear not shown. The work head may be shiftedfor taper work by screw 28 and the exterior of the mechanism showsrheostat controls 29 and 30 for the motors, a head clutch lever 31 anddoors 32 by which access is had to the interior of the mechanism,

The wheel 33 provides for hand feed supplemental to the automatic feedand reverse with which this case is concerned.

In Figures 1-3 the reversing mechanism is placed for convenience uponthe inside of the frame. This is not essential and the mechanism hasbeen shown with its location out-' t has been convenient to illustrateit in .con-

nection withdevices of these figures independently of whether they beeasily accessible or not. Q

The construction of Figure 4 has been selected for illustration becauseof its simplicity and in order to compare the character 0 snap movementin it with-that shown in Figure 6, as will later appear. Anti-frictionbearings and other constructional refinements havebeen omitted in ordernot to divert from the illustration of the new structure involved. -Thecarriage 20 is movable back and forward along the guides bf the toolupon which it is mounted so as to provide for the length of travel.required. Beneath it is located a lead screw 34 mounted in bearings 35,36. It is driven by any suitable gearing which I ihavesshown in the formof a belt 37 and pul- Zlhis lead screw 34 is provided with right andleft-hand threads 39, which consequently out each other as shown, andwhich,

as hereinafter described advance and retract right and left nuts 41, 42,respectively. When one is driving. the carriage the other is pushedahead and thus rotated upon the shaft in the direction of shaft rotationby a sleeve as later described. 'A direction of rotation of the shafthas been arbitrarily assumed to be that shown by the head and tail atthe right 'of the figure.

The screw may be single, double or other multiple thread as describedand a multiple thread is in fact illustrated. In some uses of'myinvention I plan the use of a steeper pitch for the return feed than forthe work- I ing)feed. (See Fig."7.)

do .b

k rigid wlth the carriage bviously my broad invention is not affected bythese questions of the pitch or whether the pitch of the thread is thesame for feed as for reverse. g

Thenuts 41 and 42 are provided with oppositely facing clutch members 43,'44, here shown as teeth, adapted for engagement with opposing clutchmembers 45 and 46, here also teeth, upon a block'47 surround- 'ing thelead screw. Between the lead screw and the block I place a. spacingsleeve 48.

v The block 47 is prevented from rotation y any convenient means, hereby the simple expedient of making it non-circular and enclosing itwithin a non-circular housing 49, and by which the block. is preventedfrom" turning.

The spacing of the two nuts with respect to the block is such that thereis not only enough room for the clutch members (teeth) of the block andone nut to disengage fully before the other clutch and the block engage,butthere issufiicient additional space between the brackets by which thenuts are held to their duty to permit relative movement of the unit(including the nuts) and the carria e to throw a quick stroke mechanism.

y any convenient means I control the outward limits of the positions ofthe two nuts from the carriage. This is most easily done by brackets 50and 51 extending downwardly from the carriage to engage the nuts and tolimit their movement. In the position shown in Figure 4, where the partsare engaged for movementof the carriage to the left with the directionof rotation indicated it will be noticed that there is not only spacebetween the teeth of clutch members 43 and 45 but that there is spacebetween the bracket 50 and the shoulder 52 of the nut/11. There wouldbe'corresponding space at the opposite side from shoulder 53 with drivein the opposite direction.

. The block 47' has thus a limited movement with respect to the carriagelongitudinally of the feed screw for the purpose of providing-theneutral position or of having its clutch faces engage with the clutchfaces of the nuts 41 and 42 to drive alternately in the two directions.At the same time the brackets 50 and 51 insure that the nuts cannot backaway and 7 disengage from the clutches of the block while driving. alsoprevent the disengaged nut from whirling beyond the block too far forproper en ga ing position when reversal takes place.

11 this form shown I provide a quickthrow mechanism'by which thecarriage and blockare controlled. The block which normally drives thecarriage may slide with the two nuts within the carriage when the car-'mage is stopped. The carriage may be stopped either by normal stopmechanism or by any foreign object in its path exerting a pressure inexcess of the predetermined Theypressure necessary to drive thecarriage.

The quickrow mechanism allows the block capable of wide variation andmay appear in a valveor switch-controlled outside force. I haveillustrated two forms suitable for plain mechanical structures seen inFigures \4 and 6. The one in Figure 4 comprises a spring 55 pressing aplunger 56 downwardly upon a toggle member 57 which has a seat at 58 inthe bottom of the plunger and a second seat at 59 in a recess 60 in theblock. Because of the diagonal direction of this toggle member thedriving force of the block through it against the carriage is greatestin the full stroke position shown and gradually reduces when thecarriage is stopped while the block moves forwardly in the carriage inthe direction of last carriage movement. The plunger spring is held inplace by a plug 61.

The pressure of the spring can be adj usted by screwing the plug in orout until the desired degree of pressure is attained. This adjustmentcontrols the pressure which must be exerted against the carriage toreverse it, and reversal pressure will varywidely according to existingneeds, being very great for example if the reversing mechanism beapplied to a planer, while when applied to some types of grinders it maybe small as to cause reversal by engagement across an electric lightbulb without breaking the bulb.

Obviously the angle at which the toggle member 57 is sloped in normaldriving use will greatly affect the resistance necessary for stoppage ofthe carriage and reversal even when using the same strength of spring inthe plunger mechanism. For example, in mechanism such as a planer whereheavy driving pressure and heavy reverse resistance are desirable thetoggle member would be more nearly horizontal, whereas in grindingmechanism or in a lathe or other lighter tool the toggle member would begiven a high angle such as illustrated.

At the lowerside of Figure 4 is shown a hand-reversing mechanism whoseutility would depend upon the accessibility of the structure. It wouldbe suitable, therefore, rather for an exposed reversing mechanism or forlever operation than for direct operation upon enclosed mechanism suchas is shown in the grinding machine. The handle 62 is shown connectedwith the block. By this the block can be thrown from one eX- tremity ofits movement to the other.

In Figures 1 and 2 a handle 62 is connected to the block by a leveragesystem not shown for hand-operation of the block, corresponding withmovement of the block by handle 62.

In Figure 6, I have shown a more simple form of snap actuation or fullstroke mechanismin a pair of V notches 63 and 64 within the block inwhich the V end 55 of plunger 56 is adapted to fit. The rest of thestructure is the same as in Figure 4.

In operation, with the parts in the position shown in Figure 4 and thelead screw rotating in the direction shown by the arrows, the nut 42engaging with the left-hand thread upon the lead screw intermeshes withthe clutch member 46 so that the nut can not nut 42 through sleeve 48presses the nut 41 continuously tothe left so that this nut travelsbackwardijupo'n the right hand thread, rotating.

Since the right-hand thread would tend to advance the nut 41 to theright, while the nut 42 is actually moving upon the screw to the left,the nut 41 must rotate at a greater speed relatively than the speed oftravel of the screw. If the right and left-hand screws be of equal pitchit must rotate with respect to the lead screw at a speed twice as greatas the speed of the lead screw. In Figure 7 I have shown the pitch ofthe return thread in excess of that of the feed thread on this screw inwhich case when nut 42 is driving the nut 41 would have to rotate at amuch lower rate of speed. On the other hand when nut 41 is driving thenut 42 as it is pushed ahead will rotate at a much higher rate of speed.In these forms of Figures 1' to 9the thread must be steep enough pitchfor either of the nuts to be backed off when the other is driving. Thesteeper pitch of Figure 7 is permissible for reverse movement of theparts because there is no duty other than returning the carriage or bodyand would be highly desirable in the feeding mechanism of a planer orscrew machine, to both of which this invention is adapted;

When the carriage meets with an obstruction offering it suificientresistance sothat the carriage stops, continued movement of the nut 42and block compresses the spring vertical position or when the V point ofthe plunger passes the edge between the twonotches pressure of thespring thrusts the block rapidly to the left along the sleeve 48. Thefirst effect of this movement of the block is to release the teeth atthe right hand of the block from the teeth of nut 42. Subsequently theteeth 45 at the left hand end of the block engage with teeth 43 of nut41.

Evidently the block can be thrown by handle 62 or the handle 62 toproduce the same effect or reversal canbe effected by shoving thecarriage in the opposite direction.

Figure 8 shows the parts in position with the carriage blocked by a stop66typical of any adjustable stop or obstruction-and the thrust bar invertical position ready with a slight movement of the block to the leftto cause reversal of the clutch engageme t of l er rate than the rate ofrotation of the block. In Figure 9 the carriage is shown in the sameposition but the block has jumped into clutch engagement with the nut41.

It will be noted that the position of the 5 parts in Figure 9 is thereverse of that in Figure 4, having clutch engagement at the oppositeends-of the block, one as compared with the other, and having spacingbetween the other clutch elements likewise at oppo- 10 site ends.

In Figure 9 the nut 42 is about to be drivenof them upon purelymechanical snaps.

The reversing mechanism depends for its operation upon stopping thecarriage and effecting reversal of appllcation of the feed by continuedoperatidn of the feed to be reversed.

In these two forms a member mbvable relatively'to the carriage islocated between the driving mechanism and the carriage so that continuedmovement of the driving mechanism operates the movable member vdirectly.

It may cause direct engagement of contacts,

the throwing of a mechanical or electrical switch or lever or direct orindirect action through fluid means to reversethe connections. Duringthe timethe reversal is being efiected the carriagev may be, stationary.

Whatever the lost motion mechanism used it can be applied to mechanical,electrical or Figures 1 to 9. The trailing nut is therefore fluidreversing mechanisms of any type.

The lost motion can be between slides or other relatively movableparts'ofthe carriage,

as, for example, between thefeed screw nuts and the-carriage itself, inseparated parts of the'feed screw or by providing for relative movementof the feed screw bodily in a direction reverse to that of the feed andin any-of the forms supplemental operating means may 'be used. Thus,with bodily movement of all or of any part of the feed screw the movableoperating member may, as in the other forms, make contacts, throw alever, operate a valve or act as or operate a.piston to cause fluidmovement. I

The movement of the feeding force after the'carriage stops may beresiliently pressed 5 5 or spring controlled as in Figures 4 and 6 so asto give alwaysthe same extent of com-;

pression of the carriage against its stop. It need not be spring normechanical but can be the magnetic flux from a magnet or compression ofair or gravity-operated.

' lVith the form shown in Figures 1 to 4, 8 and 9 wonderful accuracy ofreversal has been obtained, the carriage stopping at the same pointreliably within much less than 1/1000. The length of thestroke between;

ever, the trailing nut could reversals has also proved to be capable ofvery exact determination. It is not only r adapted to reverse on veryshort strokesas of one or a few thousandths of an inch but may be set tooperate to successively throw the:

reversing mechanisms where there is no measurable movement of thecarriage. The machine is capable of adjustment to reverse on extremelylight pressures and with no measurable movement of the carriage. Withthe form shown in Figures 1 to 5,7 and 8, the reaction between thecarriage and the reversing mechanism movable relatively to it isgreatest when the carriage is first stopped and reduces as the thrustconnection between it and the spring compressed by this thrustapproaches perpendicular position. 5

With the form of Figure 6 the reaction is uniform. It may be varied bythe selection illustrate the fact, true of all the forms that I the leadscrew may be movable longitudinally or not as preferred. I

in Figure 10- the lead screw 34 is of the same general character as thelead screw in the earlier figures, having right and left hand threadsupon the same shaft and having right and left nuts 52 and 53 engagingthem. In this form the nut which is operating the carriage is .theforward nut of the pair as distinguished fromthe rear nut of the pair incarried by the flanges 50', 51' respectively as shown in Figures 1 to 9.Obviously, howahead of it if desired. I

The casing 67 here corresponds generally Iwith the'block 4:7 in that itis resiliently con-' nected with the carriage 20 and is adapted to'bedriven alternatively by the nut 52' or by the nut- 53. f

The resilient connection between the casing and the carriage includesand is assembled about, a pin 68 secured in the carriage. The

end 69'iS enlarged to form a head and the larger end rests in an opening70. Upon the reduced portion 71 Iplace a collar 72 which is pressedagainst the shoulder 73 by a spring 74; At the other end the springpresses against a collar 75 which at-the limit of its movement engages"a shoulder 76 formed by fastening a sleeve .77 'upon the reducedportion 71.

shove the nut The sleeve '77 passes through an opening 78 correspondingwith the opening 70. The

enlargement --of the pin at 69. and the sleeve 77 permit movement of thecasing and carriage relatively to each other either direc- I tionbetween the limits of flanges 79 and 80 of the carriage. The pin is heldwithin flange 79 by any suitable key 81, and within the sleeve 77 by anysuitable key 82.

One of the parts rigid with respect to the carriage is used to throw thesnap actuation lever 83 for electrically snapping switch 84 to energizeeither of the electro-magnets 85 or 86. The solenoid windings embracecore 87 pivoted at 88 to the reversing lever 89. Throwing of thisreversing lever 89 about its pivot 90 to either of the two extremes ofits stroke reverses the clutch so as-to cause engagement of the clutchlever arms, 91, or 92, as the case may be, with the nuts, 52 or 53'.

A standard form of electrical reversing switch is available whichcontains a quick stroke mechanism and reverses the switch connectionswithout reversal of the position of the lever through which this hasbeen accomplished.

In operation, rotation of the lead screw in i one direction causesmovement of the car- 'ri'age in the direction which is controlled by thenut with which engagement is made by thev clutch mechanism includinglever 89. This continues in the same direction until the carriage isstopped, at which time continuing movement of the lead screw, throughthe operation of the same nut which has been doing the drivingpreviously, causes relative movement between the frame and the car-.

riage. This compresses spring 74. The compression continues until therelative move-' ment of the carriage with respect to the casing throwsthe switch lever .83 and thus throws the snap actuated switch within theelectrical switching mechanism 84, reversing the electric current andpassing the electric current through that solenoid winding from whichthe current was previously cut off.

This throws the lever 89 pivoted at 90 reversing the clutchingmechanismby which the nuts are gripped one at a time and causing thearms 91 and 92, one to grip the nut which has been inactive and theother to release the previously active nut.

The electro-magnetic snap actuated mechanism thus causes the samecharacter of operation and the same character of reversal control byreason of stoppage of the carriage as in the other forms.

In the form shown in Figure 11 I illustrate another electro-magneticreversing mechanism having a single lead screw operated to rotate indifferent directions for reversal of feed and capable of longitudinalmovement of the lead screw with respect tothe bed of the machine tool tocause reversal of the direction of rotation of the lead "screw and tothereby reverse the direction of feed.

I accomplish this by means of a shaft 34" which is threaded through andtherefore directly operates the carriage member 49. The

floating shaft is mounted in bearings 35', 36 and 93 within or carriedby the frame work both of which, through teeth 96 and 97 are driven,though in opposite directions, by a gear 98.

The shaft 34' is a floating shaft in that i has play axially and iscentered longitudinally within the play allowed by springs 99 and 100which, in order to reduce friction engage against thrust bearings 101.

Upon the shaft 34' and between the gears 94 and 95 is mounted a clutch102 splined to the shaft and having oppositely directed clutch faces103, 104 adapted to engagewith corresponding clutch faces 105, 106 upongears 94 and 95. The clutch 102 is grooved at 107 to receive the yokeend 108 of a rocker arm 109 pivoted at 110. The-yoke engages with theclutch to shift it in opposite directions. The other end of this rockerarm is yoked also, at 111 toengage with a pin 88 started in oppositedirections by lever 83' operated from any exposed part 112 of the shaft34'. It is here operated by the walls of a groove 113' in the shaft,into whichgroove the lever 83' fits.

In operation, with the parts set as shown, let us assume a direction ofclutch rotation as shown by the point and tail of the arrows, such thatthe carriage is moving to the left in the figure, that the carriageengages any stop or obstruction 66 and that the shaft continues torotate in the'same direction. When the carriage stops the shaft willcontinue to turn in clockwise direction as viewed from the right causingthe shaft to move bodily toward the right of this Figure 11 snapping theelectrical switch and electrifying the solenoid 89 while cutting off thesolenoid 88. 'The result is an immediate and quick throw of the rockerarm 109 so as to throw the clutch from the position shown to a positionat the left thereof with its left clutch face engaging the clutchmembers upon gear 94. In whatever direction gear 95 had previouslydriven this shaft gear 94 will rotate it in the opposite direction,first taking up the displaced movement of the shaft lengthwise andbringing it back to neutral. With the direction which we have assumed,gear 94 will bring the shaft back to its balanced position and will thenbegin to" tion "such as 66 which will stop it and again reverse theconnection andthe direction of travel.

It will be apparent that in all of these or other resilient 'oversrometo cause relative strength of the resistance which must be met to stopthe carriage is measured by the spring pressure which must be movementbetween the parts, i. e., in the present cases by the spring which mustbe compressed and in the form of Figures 1-9, also by the component ofpressure w 'ichis effective incompressing the spring. In grindingmachines the reversal may be effected with a very slight pressure, toolittle to reversal is .12 and showing crush a finger, but'in niachinessuch as lathes and planers in which the tool must be pushed forward toeffect the feed or make the cut the resistance to movemcnt of thecarriage necessary to,cause reversal must be greater than anything whichis to be encountered in taking the normal cut, suiting theinventionmoreto machines taking'light cuts than to machines taking heavy cuts.

That the means of effecting the actual broad and 'is not confined tomeand electrical means but vmayv inother isillustrated still further bychanical clude any the fluid actuation of the reversing mecha-' nism inFigures 12 and 13, showing. the application of outside fluid pressure inFigure the fluid merely to transient motion in Figure. 13.

' pressure is used to Figure 12 is intended to'correspond-with- Figure11 in all particulars except that fluid perform the function performedby the solenoidal form of'F-igure 11.

struction and thb shifts tothe right, the valve 84: is rotated aInsteadof the snap actuated electrical switch 35 or valve 84, thrown inopposite directions bycthe lead screw through arm 83"I provide a a snapactuated switch or valve 84. thrown by an arm '83 and'controlling thepath of inlet and exhaust to cylinders 114,- 115 from fluid jpressureinlet and exhaust 116, 117. 3 In the ,position ,shown, Tue 11 thepressure inlet is connected with corresponding to that in Figcylinder115 through pipe 118 and cylinder 114 is connected through pipe 119 withthe exhaust 117. I

'When the carriage, considered now as moving to the left. in the figure,strikes an obshaft 34' subsequently short distance before the snapactuation takes place and it is then thrown to position'to admitliquidunder pressure to pipe 120 in cylinder 114 and'to connect cylinder11 5 to exhaust through pipe 121. This throws piston 122 to the left,sweeping out the water in front of piston 123, throwing the rod or stem124 which occupies the position-of the armature 87 or 87'. acts as inFigure 12 to shift the clutch so that the shaft is'dri gear 95.

- In Figure 13, the illustration generallyparallels that in Figures 11and -12except that, as compared with both of them, the direction ofrotation of the shaft 34 is reversed the U, the axis ofthe (one onlyshown) are mount- The rest of the construction en by gear. 94 instead ofby Movement of the transmitting motion and not an outside liquidpressure.

Because of the change in the direction of rotation the carriage will bemoved in the opposite direction from that of the carriage in Figures 11and 12. and will engage'stop 66' instead of stop,66, causing the leadscrew, with continued rotation to move to the left insteadof to theright as in Figures 11 and .12 and compressing. the spring 7 1 at theleft end of the shaft (not shown in the figure) instead of 7 4' near therightend of the shaft as in the other. figures.

As a result of this movement to the left, the

, piston 125- in cylinder 126 will be moved to the left,tending'toproduce a vacuum in the space 127 The unbalanced normal airpressure upon the'outer surface I cylinder 129- will then force thispiston in, causing the liquid to flow from space 130 through pipe 131into the space 127.

The quick throw in this case is obtained by means of a snap-actuatedlever 109 of U- shape pivoted to swing about the middle of shaft 132upon which its two arms 133 ed. The lever is" actuated connected at oneend at 135 to one o and at its other end at 136 to piston by a s ring134 i the arms This point of attachment 136is thrown from a position onone side of a line 138 throu h rotating of piston 128 in.

rod 137. a

' point 135 and the shaft axis to a point on t e the'right of this line138 but the movement of the piston and its'rod .to the left will throwit to the left of this line. The a spring, whose tension willbincreaseddurmgthe shifting of the pivot, will snap the lever over to a positionat the left of that shown in the figure, carrying the clutch 102 withthe lever. upon each arm toengage the walls within. the groove in theclutch. A

Because the lead screw will be rotating and it is undesirable to rotatethe piston 125 the piston is slip-connected with the shaft. Theconnection shown is by a rod-140 terminating in a collar 141 which isfree to rotate but has slight lon 'tud'inal movement only between,

a threade projection 142 carried by the shaft and a cap 143 securedupon'the projection.

The rod a bracket 144.

, Withthe direction of rotation of the feed screw is re-' versed so thatthe carriage (not shown) will move to the left until it enga essomestop. lead screw odily toward or stem'137 is shown as guided in"vThe lever carries a roller 139 reversal of the clutch position the theright will then begin and will force the liquid out of cylinder 126 intocylinder 129,again throwing the attachment point of the spring beyondthe line 138 to snap-actuate the clutch into the position shown inFigure 13.

Figure 14 has the same direction of rotation of the lead screw andtherefore the direction of movement of the carriage for the positionshown as in Figure 13, the reverse from those seen in Figures 11 and 12.

All of the forms of reversing mechanism operate equally well with drivein either direction.

It has the same snap-actuation as Figure 13 but secures the snapactuation by direct movement of a rod or .stem 137' instead of'by fluidactuation of the fastening point of the spring. This is accomplished inFigure 14 by means of a groove 145 in the end of the lead screw, intowhich groove a roller 146 extends. The roller is carried by an arm 147connected with the rod 137' so that movement of the arm 147 and of therod 137 to the left with movement of the lead screw 34? to the left willcause the attachment point of the spring to throw beyond the line 138and 'the spring will shift the clutch.

At the endof the reversed movement a second reversal takesplace and thelead screw is shifted bodily to the right causing the clutch to bethrown to the position shown in Figure 14.

' In Figure 15 I have shown aconventional I form of lathe with a livehead 148 and gearing 149 connecting with a lead screw 34 upon which afeed reversing gear 150 is mounted.

which may be any of the types of feed gear reversing mechanisms. ThisView is shown for the purpose merely of indicating in the drawing oneother type of machine tool than the grinding tool to which my inventionmay be applied, in order to negative the idea that my invention isintended for grinding machines only, As previously stated my inventioncan be app-lied to a variety of machines, suiting best those in whichthe feed resistance to carriage-movement is low.

I have'made no attempt to show with completeness from any standpoint thevarious applications of my invention but have selected samples only,selecting diverse means by which the reversal may be accomplished inorder to make clear that the invention is of great breadth vand can bepracticed in many different ways.

I have no doubt that a great variety of other forms and means ofsecuring all or a part of the advantage of my process andmechanismchanges as come within the reasonable spirit and scope of my invention.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is 1. In a reversing mechanism for machinetools, a carriage, a feeding mechanism therefor, including a lead screwand a quick throw connection having lost motion between part of the feedmechanism and the carriage providing for continued rotation "of the leadscrew-to accumulate energy applied to the quick throw connection whenthe carriage has been stopped to terminate feed in one direction andreversing devices operated by the quick throw mechanism through takingup the lostmotion to reverse the driving connection.

2. In reversing mechanism for machine tools, a movable carriage, a feedscrew having right and left threads upon it, means for continuouslyrotating the feed screw, right and left nuts spaced upon the feed screw,movable axially of the nuts with and also with respect to the carriage,a block between the nuts having faces engaging them alternatively andlost motion snap actuation for the block forming operating connectionbetween it and the carriage.

3. In reversing mechanism for machine tools, a movable carriage, a feedscrewhaving right and left threads upon it, means for continuouslyrotating the feed screw, rightand left nuts spaced upon the feed screw,movable axially of the nuts with and also with respect to the carriage,a member between the nuts having faces alternatively engaging.

them, slip motion snap actuation connecting the member and the carriageoperated by the feed screw when the carriage is stopped and a spacerbetween the nuts adapted to back one nut off from the-member withadvances of the other nut.

4. In reversing mechanism for machine tools, a movable carriage, a feedscrew having 'right and left threads upon it, means for continuouslyrotating the feed screw, right and left nuts spaced upon the feed screw,

5. In reversing mechanism for machine tools, a movable carriage, a feedscrew having right and left threads upon it, means for continuouslyrotating the 'feed screw, right and left nuts space d upon the feedscrew, movable axially of the nuts with and also with respect to thecarriage, a spacer between the nuts adapted to back one as the otheradthe other nut.

quick operating mechanism operated by said contmued movesloping thrustconnection between the block and the carriage adapted to permit movement of the block with respect to the car riage when one nut is drivingand, with stoppage of the carriage, to snap over tothrow the block freefrom the one nut and into engagement with the other to provide drive by6. In a reversing mechanism for machine tool feeds, a machine toolhaving'a tool or work carriage, a feed screw for the carriage, drlvin'gconnections for the. feed screw, a re- 15 verslng mechanism for thescrew, a lost motion connection located in the trainbetween the drivingmechanism and the carriage providing for continued rotation of thef'sc'rew after the carriage has been stopped and a device for thereversing 'ment of the screw. 7. In a reversing mechanism for machinetool feeds, a machine tool having a tool or workcarriage, a feed screwfor the carriage, driving connections for the feed screw, turning thescrew continuously in the same directlon, a reversing mechanism, a: lostmo-- tion connection located in the trainbetween the driving mechanismand the carriage providingfor continued rotation of the screw after thecarriage has been stopped and a quick operating device for the'reversing mechanism controlled by said continued movement of the screw.

8. In a machine tool, a tool or work .carriage, a traversing means forthe carriage and-astop for the carriage in combination with drivingmeans for operating the'trav ersing means, and means actuated by thecontinued movement of the traversing means after the carriage hasengaged the stop.'to reverse the direction of movement of said carriage.9. In a machine tool, a tool or work carriage, mechanism forcausingtraverse ofthe carriage, a stop for the carriage, means for driving thetraversing mechanism, lost motion connections between the dri ingmeansand the carriage'adapted to continue to op-i erate the traversingmechanism after the carriage has stopped, and means actuated by thetraversing mechanism during the'time the carriage is stopped forreversing the direction of traverse efi'ected by said traverse means.

v i I L .10. In a machine tool a tool or work carriage, mechanism forcauslng traverse of the carriage, a stop for the carriage, means forently retardeddost motion connection betweenthe traversing mechanismand-the car riage, driving means for the traversing mechanism andreversing connections for the 5 carriage operated through the lostmotion screw. continues; to rotate this resilient opposition to quicklyreverse driving the traversing mechanism, a resilLv neea'ztsa Iconnection by continued movement of the traversing mechanism.

11. In a machine tool, a tool or work carriage, a traversing screwtherefor, means for operating the screw, lost motion connections. in thetrain between the operating meansand the carriage whereby the traversingscrew with continued operation takes up the lost motion and meanseifected through the taking up of the lost-motion for reversing thedirection of traverse of the carriage.

12. In a machine tool, a tool or work carriage, a stop therefor, acontinuously rotatable right and left thread traversing screw, a nutlocated in each thread, a clutch carried by each nut, means-locatedbetween the two clutches having. clutches adapted to coopoperates thequickthrow device and changes the clutch connection 13. In a machinetool,-a-tool or work carriage, traversing means for causing the carriageto. move along the length of the. machine, lost motion connections inthe train between the traversing means and the carriage whereby withcontinued operation of the traversing means the lost motion is taken upand means efiected through the taking up of the lost motion forreversing the direction of traverse of the carriage. A p

'14. In operatlon of a reversing mechanism embodying a carriage, a feedscrew therefor and connections between the feed screw and carriage foroperating thecarria'ge in oppo- 7 site directions, the noveltywhichconsists in resiliently opposing bodily movement of the,

connections between the screw and carriage when-the. carriage is stoppedand the feed and in utilizing the connections.

15. In feeding and reversing mechanism, for machine tools,'a carriage, alead screw engaged therein and bodily movable in an axial direction,spring means opposing movement in each direction, facing gears upon theshaft constantly driven in opposite directions a clutch between thegears and movable axially of the shaft, and snap actuation for theclutch thrown bymovement of the shaft in reaction against the carriagewhen the carriage engages a stop.

' 16. feeding and reversing mechanism. for machine tools, a carriage, alead screw engaged therewith and bodily movable in an axialdirectiomspring means opposing movementrin each direction, facing gearsupon the shaft, constantly driven in opposite directhe movable shaft toset. the snap actuating mechanism.

17 In feedin and reversing mechanism for machine too s, a carriage, alead screw 5 engaged therewith and bodily movable in an axial direction,spring means opposing move- I ment in each direction, facing gearsupon'the shaft constantly driven in opposite directions, a clutchbetween the gears and movable axially with the shaft, snap actuation foroutside setting force for the snap actuation and valve control for saidoutside force movableb the movableshaft. y 18. 1 feeding and reversingmechanism for machine tools, a carriage, a lead screw on aged therewithand bodily movable in an anal direction, spring means opposing movementin each direction, facing gears upon the shaft, a constantly drivenclutch between the gears and movable axially of the shaft, snapactuation for an outside actuating force applicable to the movement ofthe clutch and means for applying the outside force with movement of theshaft.

19. Infeeding and reversing mechanism for machine tools, a carriage, alead screw engaged therewith and bodily movable in an axial direction,spring means opposing so movement in each direction, facing gears uponthe shaft constantly driven in opposite directions, a clutch between thegears and movable axially with the shaft anda snap actuated control setby movement of the lead screw for throwing the clutch.- 1

20. In feedin' 'and reversing mechanism for machine too a carria e, alead screw' engaged therewith and b0 ily movable in an axial direction,spring means opposing 0 movement in each direction, driving means forturning the screw in ofpposite directions, a clutch movable axially othe shaft to engage the driving means, snap actuation mechanism forthrowing the clutch and connections be- 5 tween the shaft and the snapactuating mechanism for settin and tri mg the same.

F D T. RAULE.

